1. Field of the Invention
The invention relates to hoses. In one of its aspects, the invention relates to a high-pressure hose for cleaning buried pipelines which can be accurately located along its length in the pipeline. In another of its aspects, the invention relates to a high-pressure hose for cleaning buried pipelines wherein the three-dimensional position of the hose can be accurately determined along its length in the pipeline. In yet another of its aspects, the invention relates to a method for determining the position of a high pressure hose within a blocked underground conduit.
2. Background Art
Buried pipelines, such as sewer lines, typically require periodic maintenance and cleaning, which is accomplished by inserting a high-pressure hose into the sewer line and introducing a pressurized cleaning fluid through the hose to clean and flush the sewer line. Typical sewer lines may be buried at depths ranging from 5 to 13 feet below grade, and may be too small to enable a worker to enter and directly observe the location of the hose. During sewer maintenance and cleaning procedures, it is often difficult to accurately determine the location of down-hole blockages. At present, a commonly used method to determine a blockage location involves sending a second probe through the pipeline or using a contact measuring device that rolls on the hose as it dispenses in order to establish the length of hose introduced into the line. However, these methods only provide approximate measurements.
It is frequently desirable to know the route the hose takes. This is particularly important when an obstruction has been encountered and must be removed by excavating down to the pipeline at the point of the obstruction. If an unserviceable obstruction is encountered and digging is required, the accurate surface location of the obstruction must be established. Sewer lines do not always run in straight lines, and some drain networks can be complex, with many branches, thus complicating the search for an obstruction. Branching sewer lines may require maintenance, and the status of each branch must therefore be established during the maintenance process. Accurate location of the hose is necessary in these circumstances.
Common locating systems are only capable of locating the metal, or fitting, end of the hose. The location of the hose itself is indeterminate. Inaccurate location of the hose may contribute to missed obstruction excavations, damage to adjacent sewer networks during excavation to an obstruction, or missed or improperly maintained branches.
U.S. Pat. No. 5,243,128, to Marcoz, discloses a mobile sewer cleaning apparatus with a flexible, multi-layer hose having markers with magnetic or electrical characteristics different from those of the hose. As the hose is paid out, the markers pass through an electromagnetic detector which provides information on the length of the hose paid out.
U.S. Pat. No. 5,469,916, to Sas-Jaworsky et al, discloses a system for depth measurement in a wellbore with multi-layer tubing having detectable indicia spaced along the length thereof, and a depth measuring device with sensors appropriate for the type of indicia used. The depth measuring device counts the number of indicia that pass the device, thereby measuring the depth of the tubing in the wellbore.
Patent Abstracts of Japan Publication No. 10026267 discloses a multi-layer hose with inner and outer layers and a woven reinforcement layer therebetween. Metal wires are wound around one of the reinforcement threads at preselected intervals to form markers along the hose. As the hose is paid out, it passes through a metal sensor that detects a change in magnetic field to measure the length of the hose.
Patent Abstracts of Japan Publication No. 06241770 discloses a hose length measuring system for manufacturing hose of a preselected length. The hose has spaced markers that can be read by a sensor. Data from the sensors is sent to a data processor which calculates the length of the hose.
U.S. Pat. No. 4,446,892, to Maxwell, discloses an apparatus for monitoring lengths of hose with individual multi-layered hose sections that are interconnected. The hose sections are made, in part, of a synthetic rubber tube and an overlying textile ply. A coil of fine wire is wrapped around the tube beneath the textile ply, and is connected to a sensing unit. The introduction of fluid between the tube and the textile ply due to a rupture of the tube will alter the electromagnetic characteristics of the wire, which will be detected by the sensing unit.
U.S. Pat. No. 5,036,210, to Goodman, and U.S. Pat. No. 6,092,558, to Maccario, disclose underground pipe with magnetically detectable materials incorporated therein or thereon so that the pipe can be detected from above ground by a magnetic field detection apparatus.
U.K. Patent Application Publication No. 2,183,044 discloses an apparatus for measuring the displacement of elongate elements, such as wire rope, having helically coiled strands whose ferromagnetic properties vary periodically along its length. A polarizing magnet and a magnetic field sensor are mounted next to the wire rope. As the wire rope passes the magnet, the sensor detects the variation in the magnetic field and measures the displacement of the wire rope. A second sensor can be used to determine the direction of travel.
It would be desirable to have a flexible high-pressure hose which can be introduced into buried pipelines and whose exact location can be determined from above ground.